What happened
On September 24, 1999, a Tecnoflug Piccolo motor glider, registration HB-2133, was engaged in a cross-country and gliding flight originating from Triengen. During the flight, while over southern Germany near the Swiss border, the pilot contacted the Zurich Flight Information Sector to report feeling medically unwell. Although the pilot initially considered an immediate emergency landing in Germany, he later reported feeling slightly improved and decided to proceed toward the Fricktal-Schupfart airfield.
Approximately one hour after the initial report of illness, the aircraft approached runway 26 at Birrfeld. Witnesses observed the aircraft performing extreme pitching motions—described as pumping—before plunging into the ground at a very steep angle. The impact resulted in the fatal injury of the pilot and the total destruction of the aircraft. No other injuries or third-party casualties were reported.
The investigation
The investigation, conducted by the Swiss Transportation Safety Investigation Board (SUST) in collaboration with local police and forensic institutes, examined the wreckage and the pilot's medical history. Technical inspections of the HB-2133 revealed no pre-existing mechanical defects, corrosion, or structural failures in the flight controls or airframe that could have caused the loss of control. The aircraft's weight and balance were within limits, and the engine was functioning correctly.
Medical examinations of the pilot's remains identified pre-existing cardiac conditions capable of causing circulatory disturbances, such as dizziness or even near-collapse, even under low physical strain. While toxicology reports showed the presence of a blood-sugar-lowering medication, there was no evidence of impairment due to external substances or significant metabolic instability.
Findings
- The primary cause of the accident was the loss of control of the aircraft during final approach.
- It is highly probable that the pilot experienced a momentary loss of consciousness or was incapacitated by physical pain or malaise.
- The pilot underestimated his medical condition by continuing the flight after experiencing symptoms that had only temporarily stabilized.
- A failure to prioritize an early emergency landing may have been influenced by concerns regarding flight formalities, such as a missing flight plan, or an aversion to the inconvenience of landing at an unfamiliar airfield in another country.